Apparatus for producing metal powder



Sept. 18, 1945. .1. E.'sl| vAsY ET AL APPARATUS FOR PRODUCING METALPOWDER Filed Dec. l5, 1945 2 Sheets-Sheet l ...riiimmmwy 1 lnucntors B,m m m NM1 l mm M L my A 5r Nm #u 0 JMW /Ho/v PowoER PHoDl/cr Sept' 18,1945 Y .1. E. slLvAsY ET AL 2,384,971

APPARATUS FOR PRODUCING METAL POWDER Filed Dec. l5, 1945 2 Sheets-Sheet2 Snuentors:

JO//VEJYL VAJY i Cttorneg Patented Sept. 18, 1945 UNITED ,l STATESPATENT oFElcE APPARATUS FOR-PRODUCING METAL POWDER John E. Silvasy andLouis Taylor, Youngstown, Ghio Application December 15, 1943, Serial No.514,578

2 Claims. (01.266-24) a low temperature reductionrprocess.

A further object of the invention is the provision of apparatus for theproduction if iron powder directly from ore by a thermochemical process.

A still further object of the invention is the provision of a means forproducing iron or other metallic powders directly from ore wherein onlyAhydrocarbon gas is added in carrying out the said method.

A still further object of the invention is the provision of apparatusfor producing iron powder directly from ore by a thermochemicalreduction, and wherein only hydrocarbon gas is added in the process ofreduction.

vA still further object of the invention'is the provision of apparatusfor cooling the metallic powder produced and which apparatus constitutesa. step in the production of the metallic powder.

A still further object of the invention is the provision of means forseparating the metallic powder produced from the gaseous atmosphere inwhich it has been carried so as to enable its accumulation to facilitateremoval of the metallic powders produced.

'I'his invention relates to powder metallurgy and particularly to theproduction of powdered metal directly from ore suitable for use invari`- ous powder metallurgy practices. It has been determined thatpulverized ore can be mixed with hydrocarbon gas, as by being fed from ahopper into a mixing chamber into which the hydrocarbon gas issimultaneously admitted, and the hydrocarbon gas and pulverized oremixture then directed into an externally heated retort, in which thereduction takes place. As the pulverized ore is suspended in thehydrocarbon gas so thatindividual particles thereof are surrounded bygas. the reduction is accomplished quickly and uniformly by athermochemical process which 'depends upon the complete cracking of thehydrocarbon gas wherein .the gas separates into its verized. Thereduction takes place due to the fact that the large surface areapresented by the oxide ore cloud to the hydrocarbon gas affords a veryconvenient surface upon which the molecular sized carbon particles cansettle as they are freed from the hydrocarbon gas. When the ore powderreaches the temperature necessary for reduction the said carbon presentwill 'take up the oxygen from the oxide ore and liberate carbon l0monoxide (CO) gas and free iron powder. The

carbon monoxide (C0) gas, being a reducing agent, works on any unreducedoxide converting it to free, iron and itself to carbon dioxide (CO2)gas. The free hydrogen (H2) liberated by the 1l cracking of thehydrocarbon also aids in the reduction as it liberates free iron and H2Oas vapor. Metal powders other than iron, which metals are reducible bycarbon and hydrogen at temperature ranges of 80G-1050 degrees can alsobe pro- $0 duced by the method herein disclosed. Such which will appearas the description proceeds,

the invention resides in the `combination and arrangement of parts andin the details of construction hereinafter described and claimed, itbeing understood that changes in the precise em- 30 bodiment of theinvention herein disclosed can be made within the scope of what isclaimed without departing from the spirit of the invention.

The invention is illustrated in the accompany- 35 ing drawings wherein-4 Figure 2 is an enlarged detailed illustration of a magnetic separatorforming a pari. of the apparatus disclosed in Figure 1.

Figure 3 is a cross sectional elevation taken on lines 3 3 of Figure 2.

5 By referring to the drawings and Figure 1 in particular, it will beseen that a vertical retort Il which in actual practice is preferablyseveral times greater in height than in width, is provided with acombustion chamber Il formed there- 5 about by an enclosure I 2preferably formed oi header it in communication with a plurality ofburner nozzles I 5 which extend into the combustion chamber ii. It willthus be observed that fuel supplied through the header it and the burnernozzles I5 may be burned in the combustion chamber i i so as toestablish desirable temperatures within the vertical retort Iii aboutwhich the combustion chamber ii is formed. A thermocouple well I6 ispositioned partially within the vertical retort I0 in a gas-tight mannerso that suitable instruments may be employed in connection therewith tocontrol the temperature within the vertical retort iii.

In order that a mixture of pulverized metallic ore and suitablehydrocarbon gas such as natural gas may be supplied to the verticalretort I@ as by way of an opening I'i at the uppermost end thereof,means has been provided for supplying suitably pulverized metallic oreand a hydrocarbon gas and suitably mixing the same and delivering themixture of ore particles and gas to the vertical retort l0 through the'opening i'i in the top thereof. Such means may consist, for example, ofa hopper i8 equipped with a screw type conveyor i9, which conveyor I9 isdriven through a flexible coupling 20 by a suitable power source 2i suchas an electric motor. Finely pulverized iron ore, indicated by thenumeral 22, in the hopper I8, is delivered by the screw type conveyor i9 to a Venturi tube type mixing chamber 23 into which the hydrocarbongas is admitted through a Venturi jet 24 from a regulating valve chamber26 in a regulating valve 2l', the regulating element of which isindicated by the numeral 28 and is shown adapted for manual regulationby means of a hand wheel 29, it being obvious that automaticallyregulated valves can be employed at this point. Hydrocarbon gas undersuitable pressure is supplied to the valve chamber 26 by way of tubularconnections 30 which in turn communicate with a suitable pump orcompressor 3I, hydrocarbon gas being supplied to the pump or compressor3| by way of tubular connections 32 in which a control valve 33 ispreferably located. l

By again referring to the mixing chamber 23 it will be observed thathydrocarbon gas passing through the Venturi jet 24 enters the mixingchamber 23 and will carry the pulverized ore vparticles being introducedthereinto by the conveyor screw I9 into an elbow 34 which is ailixed toand communicates directly with the interior of the vertical retort I0 byway of the opening I1 therein. It will thus be observed that the inelydivided ore particles in a practical suspension of hydrocarbon gas areintroduced into the uppermost portion of the vertical retort i0 fromwhence the natural tendency will be to settle downwardly to thelowermost section thereof. As a suitable reducing temperature ismaintained in the vertical retort I0 by means of fuel yburning in thecombustion chamber II which surrounds the vertical retort I0, the'reductionof the metal- .lic ore is accomplished.

The pulverized ore is suspended in the hydrocarbon gas so that theindividual particles thereof are quickly and uniformly reduced by sthermochemical process which depends upon the complete cracking'of thehydrocarbon gas thereby separating the gas into its constituentelements, chiefly hydrogen and carbon. The carbon separates as a soot inan extremely fine solid state. As iron oxides, for example', arereducible by carbon and hydrogen gas at temperature ranges of between oand 1050 C.. the oxide ore par ticles are reduced practicallyinstantaneously as the surface area presented by the oxide ore particles ailords a very convenient surface upon which the molecular sizedcarbon particles can settle as they are freed from the hydrocarbon gas.'I'he pulverized ore rapidly reaches the temperature necessary forreduction (approximately 1000) The carbon present taires up the oxygenfrom the oxide ore and in turn liberates carbon monoxide (CO) gas andfree iron powder. The gas (CO) being a reducing agent, works on anyunreduced oxide and converts it to free iron and itself to carbondioxide (CO2) gas. Free hydrogen (Hz) is liberated by the cracking ofthe hydrocarbon and this also aids in the reduction of the pulverizedore as it liberates free iron and water vapor.

The amounts of pulverized ore and hydrocarbon gas being regulated in themixing chamber 23 are present in proper amounts for carrying through theprocess of reduction and the result is, therefore, a completely reducediron powder. The process also produces a relatively small quantity ofunreduced non-metallic particles, consumed gas consisting of carbonmonoxide (CO) gas, carbon dioxide (CO2) gas, free hydro-D gen (H2) andwater vapor in small percentages which prevent reoxidation of the ironpowder.

The free iron powder together with the gases resulting from thereduction process and minute quantities of unreducible foreign particlespass from the vertical retort I0 by way of an opening 35 in thelowermost portion thereof directly into a heat exchanger 3B by way of anopening El in the top thereof. In the heat exchanger @t a circulatingwater cell heat exchanger unit 3B is positioned which is supplied withcirculating cooling water and is so formed that a plurality of tubularopenings are positioned vertically therethrough and which verticalopenings are indicated by the numerals 39. The iron powder and gases arethereby caused to descend through the tubular openings 39 in the heatexchanger 36 and give up a considerable amount of the heat retained fromthe reduction process.l A thermocouple well 40 is provided in the heatexchanger so that suitable controls may be effected depending upon thetemperatures therein.

The iron powder and gases pass from the heat exchanger 36 by way of anopening 4i in the lowermost portion' thereof and into a radialdistributor 42 which in turn is positioned within a depending enclosure43, a portion of which consists of a. magnetic separator 44 which iscircular in shape and positioned about the delivery opening of theradial distributor 42 through whicho the iron powder is delivered. Themagnetic separatoris, as may be seen by referring to Figure 2, formed ofa plurality of alternate layers of dat. circular coils and soft steelplates, the coils being indicated by the numerals 44 and the steelplates by the numerals 45. A circular water jacket 46 is positionedaround the outer surface of the magnetic separator and is adapted toconvey circulating water as a cooling agent thereabout. `"li'he softsteel plates 45 are provided for the magnetic circuits which arecompleted through a shell 41 and the gaps 43. Individual magneticcircuits 48 are established. n thin shell l50 is placed in the insidebore of the magnet, the shell being formed of a non-magnetic material sothat the flux spreads out from one pole to another bridging the gaps andattracting the iron powder and holding it against the non-magnetic shell50. The magnetic separator is divided into two or more circuits, one ofeach being connected to a common D. C. power line the other circuitlines are independently controlled by switches 452 which indicate thatone or more circuits are on while another is open thus dropping the ironpowder accumulated thereby.

It will be obvious that certain modifications of the apparatus disclosedwill permit the reduction of non-magnetic powdered metals. SuchmodivI'lcations consist of substituting conventional dust collectors forthe magnetic collector so as to separate non-magnetic metal powder fromthe gas present. the art.

The switches 52 are used to alternate the energization of the two ormore magnetic circuits of magnetic separator and thereby serve tocollect and hold the iron powder delivered through the radialdistributor 42 and permit the gas in which they have been carried topass outwardly from the area about the radial distributor l2 through atubular channel 53. 'I'he iron powder collected by the magneticseparator is dropped from time to time upon the alternate energizationof. the two or more circuits of the magnetic separator heretoforedescribed, directly into a receiving hopper 54 which is of sumcient sizeto permit a suilicient quantity of the iron powder to be maintainedtherein to effect a gas seal with respect `to a. screw type conveyor 55driven by a motor 55 which communicates with the hopper 5t at the bottomthereoi` and which is adapted to deliver the iron powder therefrom Thepowder delivered therefrom constitutes the productiof the method andapparatus of this invention.

- In order that additional hydrocarbon gas may be added to the gaseousmixture being separated from the metal powder in the magnetic separatort5, a gas inlet, controlled by a valve 51, communicates with theuppermost portion of the receiving hopper 54 by way of an opening 58therein and hydrocarbon gas introduced thereinto flows upwardly throughthe magnetic separator 45 and joins the gases therein and leaves thearea of the magnetic separator by way of the tubular channel 53. Thetubular channel 53 cornmunicates with a gas cleaner 59 where suchnonmagnetic particles as may have been carried along with 'the gasmixture are separated therefrom. The gas cleaner is similar. toa'conventional dust collector and is known in the art. A clean gasmixture leaves the gas cleaner 58 by way of a tubular channel 50 and iscarried thereby to a pump or compressor 5I which is also provided withan air inlet 52 so that a proper combustible mixture may be formed anddelivered therefrom by way of a tubular channel 53 at a desirablepressure to the header Il from whence it will ilow through the burnernozlzes' I5 into the combustion chamber II formed about the verticalretort I0. The combustion taking place in the combustion chamber Il,therefore', utilizes Such devices are well known in cal reductionprocess is utilized for heating purposes in the apparatus.

y It will thus be seen that a practical and eilicient method ofproducing metal powders directly from their ores has been disclosed ashas apparatus suitable for. carrying out the method. It has been letermined that the reduced metallic powder is prevented fromagglomerating into larger particles by the surrounding gas and it isalso prevented from sticking to the walls of the vertical retort I0 byradiation pressure from the walls which action is further assisted bythe fact that the ore is rapidly moving downwardly carried by the gas.As has been stated, natural gas is preferred as the hydrocarbon reducingagent and fuel where available. However, manufactured hydrocarbon gascan be used if *freed from sulphur compounds. The` apparatus can beoperated continuously as long as suitable ore is deposited in the hopperand suitable hydrocarbon gas is supplied the mixing chamber, and themagnetic powder produced is removed from the receiving hopper. It willbe observed that the supplementary gas supplied through the gas inletcommunicating with the receiving hopper is admitted in controllablequantities therethrough for the dual purpose of further cooling thepowder held by the magnetic separatori and to provide additional fuelfor heat in the combustion chamber Il to supplement the partiallyconsumed gas coming from the vertical retort so that the requiredtemperature may be maintained in the vertical retort l0. In actualpractice pyrometer and electrically controlled valves are employed andthe mixing and measuring of the ore and gas are accurately controlled.Flow meters, pressure gauges, fuel gas analyzers and other conventionalitems of furnace equipment are not shown or described as the same arewell 4o known in the art and their application to the apparatusdisclosed is readily understood by those familiar with the art.

It will thus be seen that as illustrated the apparatus can reducemagnetic metals and separate them by the magnetic type separator shown.The apparatus can be modified to reduce and separate any similarlyreducible non-magnetic metal. It will be observed that powderl of anyparticle size can be produced as the easily controlled particle size ofthe ore entering the hopper I8 is maintained throughout the process.Powder produced will be of a spongy texture which is desirable infurther processing of the powder directly or indirectly into articles.The magnetic powder produced is of exceptional high-purity, while thecost of producing the metallic powder is very low. The process is rapidand continuous. ,l

Having thus described our invention, what we claim is:

1. Apparatus for reducing metallic oxide ores to pure metallic powder,said apparatus consisting 'of a closed retort, means for mixingpulverized ore and hydrocarbon gas soas to cause the pulverized ore tobe carried in a gaseous suspension, means for introducing the gaseoussuspension of pulverized ore into the said retort and means forexternally heating the said retort so as to establish reductiontemperatures therein,means in communication with said retort forreceiving the reduced metallic powder and gaseous by-products forcooling the same and means in connection with the said cooling' meansfor separating the metallic powder from the gaseous by-products, meansin connection with the said separating device for receiving theseparated me'taiic powder and means in communication with the seidseparating device for receiving'the tay-products, and means fordirecting` the-said tgl-products for foei for the external meeting osaid retort.

2. Apparatus for continuous@ producing free iron powder from iron ore,seid apparatus iik* gaseous ley-products of reduction for cooling the g@sement. separator in-'c'ommuniceton' with the said heat eschsunger` forseparating the seid iron powder' from-the said gaseous tay-products ofseduction and te hopper rfor collecting the seid separated ironlpowder,l e ges cieaner in comw municstionwith the said separator forui'tner treating the said. gaseous oy-products and e, compressosincommunication with the vseid ges eieaner for the purpose of removinggaseous 'eyproiucts therefrom and orcioly supplying the to the saidcombustion chamber by wey on e piurality of burner nozzles inassociation thm with, a ue in association with the c mtos' chamber forremoving the products of en bastion and a suppiemeutey iuei ges inicommunication with the seid eppe'etus for s piying supplementary .fuelges to the seid comea bustion chamber.

